1. Field of the Invention
The present invention relates to an image exposing device which, on the basis of image data, modulates light beams output from three light sources having respectively different wavelengths, and scans-exposes a photosensitive material.
2. Description of the Related Art
Conventionally, in an image exposing device which exposes an image while scanning on a photosensitive material light beams of three different wavelengths output from semiconductor lasers, the wavelengths of the lights output from the semiconductor lasers and the spectral sensitivity characteristics of the photosensitive material which is used are set to match each other.
However, in a case in which a photosensitive material having special spectral sensitivity characteristics is used, semiconductor lasers matching the special spectral sensitivity characteristics must be used. This leads to an increase in cost. Further, maintainability, e.g., the introduction of a new image exposing device, replacement, repair, and the like, deteriorates due to the use of semiconductor lasers which are not widely used. Moreover, the structure of the optical system becomes complex, and the assembly workability deteriorates.
Examples of semiconductor light sources which are widely used include semiconductor lasers which are used for reading CDs (compact discs) and have a light-emitting peak wavelength of around 78 nm, and semiconductor lasers which are used for reading DVDs (digital video discs) and have a light-emitting peak wavelength of around 635 nm.
Examples of widely-used semiconductor lasers which have been put into actual use include InGaP semiconductor lasers having a light-emitting peak wavelength in a vicinity of 670 nm, InGaAsP semiconductor lasers having a light-emitting peak wavelength in a vicinity of 690 nm, and semiconductor lasers having light-emitting peak wavelengths in a range of 670 nm to 710 nm.